Disclosed is a semiconductor package comprising a lower semiconductor chip and upper semiconductor chips vertically stacked on a top surface of the lower semiconductor chip. The upper semiconductor chips include first upper semiconductor chips and a second upper semiconductor chip. The first upper semiconductor chips are between the lower semiconductor chip and the second upper semiconductor chip. A thickness of each of the first upper semiconductor chips is 0.4 to 0.95 times that of the lower semiconductor chip. A thickness of the second upper semiconductor chip is the same as or greater than that of the first upper semiconductor chip. A total number of the first and second upper semiconductor chips is 4n, wherein n is a natural number equal to or greater than three.